DE2746269C3 - Microscope objective for 40x magnification - Google Patents

Description

The invention relates to a microscope objective for 40x magnification, which consists of a first

Lens element in the form of a thick meniscus-shaped divergent lens with a concave surface on the object side, from a second lens element in the form of a meniscus-shaped convergent lens with a concave surface on the object side, a third lens element in the form of a convergent cemented element, a fourth lens element in the form of a convergent cemented element and a fifth lens element in the form of a dispersing meniscus-shaped cemented limb with a concave surface on the face side.

From DE-OS 24 05 446 a microscope objective of this type is known which has a numerical aperture N.A. = 0.65 and has a field of view of IH = 3.

Objectives for microscopes with a similar structure are also known from US Pat. No. 3,481,665.

The invention is based on the object of specifying objectives of this type which, even with a considerably enlarged numerical aperture of N.A. = 0.7 and an enlarged field of view (IH = 3.2 ~ 3.5) have good imaging properties.

In the case of lenses of the type mentioned at the outset, this is achieved according to the invention by the features listed in the characterizing part of the claims.

The invention will now be explained using lenses according to the invention with reference to the drawings. In the drawings shows

1 shows a schematic sectional view through the microscope objectives according to the invention,

2 shows the correction curves of a first objective according to the invention,

3 shows the correction curves of a second objective according to the invention,

4 shows the correction curves of a third objective according to the invention,

5 shows the correction curves of a fourth objective according to the invention,

6 shows the correction curves of a fifth objective according to the invention,

7 shows the correction curves of a sixth objective according to the invention,

8 shows the correction curves of a seventh objective according to the invention,

9 shows the correction curves of an eighth objective according to the invention,

10 shows the correction curves of a ninth objective according to the invention.

The microscope objectives according to the invention have the structure shown schematically in FIG. They consist of five lens elements, the first being a thick meniscus-shaped diverging lens with a concave surface on the object side, the second lens element a meniscus-shaped converging lens with a concave surface on the object side, the third lens element a cemented element with positive refractive power, the fourth lens element also a cemented element positive refractive power and the fifth lens element is a meniscus-shaped diffusing cemented element with a concave surface on the object side.

During the development of the objectives according to the invention, compliance with the following conditions has proven to be essential for the reasons explained in more detail below.

(1) - (9)

r [deep] 1 and r [deep] 2 are the radii of curvature of the surfaces of the first lens element,

r [deep] 4 is the radius of curvature of the image-side surface of the second lens element,

r [deep] 5 is the radius of curvature of the object-side surface of the third lens element,

r [deep] 8 is the radius of curvature of the object-side surface of the fourth lens element,

r [deep] 11 and r [deep] 13 are the radii of curvature of the object-side and image-side surface of the fifth lens element,

d [deep] 1 is the thickness of the first lens element,

d [deep] 11 and d [deep] 12 are the thicknesses of the lenses forming the fifth lens element,

d [deep] 10 is the air gap between the fourth and fifth lens element,

n [deep] 1 is the refractive index of the first lens element,

n [deep] 2 is the refractive index of the second lens element,

n [deep] 3 is the refractive index of the lens arranged on the object side in the third lens element,

n [deep] 5 is the refractive index of the object-side lens in the fourth lens element,

n [deep] 7 and n [deep] 8 are the refractive indices of the lenses forming the fifth lens element,

small Ny [deep] 3, small Ny [deep] 4, small Ny [deep] 5 and small Ny [deep] 6 are the Abbe numbers of the lenses forming the third and fourth lens element, respectively.

Of these conditions, conditions (1) and (2) serve to determine the refractive power and the deflection of the first member, which is a diffusing meniscus-shaped single lens. In conjunction with conditions (3) and (4), the meaning of which will be explained in more detail below, these conditions also serve to eliminate the curvature of field by correcting the Petzval sum of the overall lens and also to improve spherical aberration and coma of the overall lens correct. When the expression given in condition (1) is larger than the upper limit of condition (1), the curvature of field is overcorrected and lateral aberration of oblique rays is undercorrected. If the expression given in condition (1) is smaller than the lower limit value, the curvature of field is under-corrected and lateral aberration is over-corrected. If the expression limited by the condition (2) is larger than the upper limit value of the condition (2), the curvature of field is undercorrected and lateral aberration due to oblique radiation is overcorrected. if the expression limited by condition (2) becomes smaller than the lower limit value, the curvature of field is overcorrected and lateral aberration due to oblique radiation is undercorrected. Conditions (3) and (4) are used to determine the refractive power and the deflection of the fifth lens element which is a diffusing meniscus-shaped cemented element made of two lenses. Together with the above-mentioned conditions (1) and (2), these conditions serve to remove the curvature of field and the astigmatism difference by correcting the Petzval sum. In addition, these conditions in conjunction with condition (6) serve to eliminate coma. When the expression limited by the condition (3) is larger than the upper limit of the condition (3), the curvature of field and the astigmatism difference are overcorrected and the zonal aberration of the spherical aberration due to oblique rays is large. If the term limited by condition (3) is smaller than the lower limit value, the curvature of field and astigmatism difference are undercorrected.

If the expression limited by the condition (4) is larger than the upper limit value of the condition (4), the curvature of field and astigmatism difference are over-corrected and the spherical aberration due to oblique rays is large. If the expression limited by condition (4) is larger than the lower limit value, the curvature of field and astigmatism difference are undercorrected.

The condition (5) serves to limit the deflection of the third lens member, which is a convergent putty member. This condition is mainly intended to correct the astigmatism difference well and also to eliminate coma. If the term limited by the condition (5) is larger than the upper limit of the condition (5), the astigmatism difference is undercorrected and it becomes impossible to correct the remaining astigmatism difference well by other factors. In addition, inward coma becomes large. If the term limited by the condition (5) is smaller than the lower limit value, the astigmatism difference is overcorrected and the outward coma becomes large.

Condition (6) is provided for limiting the air gap between the front lens group having the first, second, third and fourth lens elements and the rear lens group consisting of the fifth lens element. This condition is primarily used for good correction of coma caused by oblique radiation. If the term limited by the condition (6) is larger than the upper limit of the condition (6), a coma is caused. When the term limited by the condition (6) is smaller than the lower limit value, inward coma is caused. If the term limited by the condition (6) is smaller than the lower limit value, outward coma is caused.

Condition (7) relates to the achromatic lenses in the front lens group and is used for good correction of the longitudinal and transverse chromatic aberration of the overall objective. When the expression limited by the condition (7) is larger than the upper limit of the condition (7), longitudinal chromatic aberration is overcorrected too much by short-wavelength marginal rays if lateral chromatic aberration is corrected satisfactorily, and blurring occurs in the image. As a result, the image contrast becomes unfavorable. If the term limited by the condition (7) is smaller than the lower limit value, an undue undercorrection of lateral chromatic aberration results if the longitudinal chromatic aberration is corrected satisfactorily.

Of the other conditions, condition (8) serves to limit the refractive power of the second lens member which is a positive meniscus lens, and this condition is intended to correct spherical aberration and compliance with the sine condition of the objective well. If the term limited by the condition (8) is larger than the upper limit of the condition (8), spherical aberration is overcorrected and the zonal aberration of the sine condition is large. If the term limited by the condition (8) is smaller than the lower limit value, spherical aberration is undercorrected. When an attempt is made to correct spherical aberration by other factors, zonal aberration becomes large. In addition, the balance between the sine condition and spherical aberration is disturbed, and asymmetrical aberration by oblique rays is caused.

Condition (9) relates to the deflection of the fourth lens member. This condition is mainly used to correct the astigmatism difference of the lens like the aforementioned condition (5). Regarding the correction of the astigmatism difference, condition (5) is the main condition and condition (9) is the secondary condition. Therefore, for correcting the astigmatism difference, condition (5) is more effective and essential than condition (9). If the term limited by condition (9) is larger than the upper limit of condition (9), the astigmatism difference is undercorrected and inward coma becomes large. If the term limited by the condition (9) is smaller than the lower limit value, the astigmatism difference becomes overcorrected and the outward coma becomes large.

Lens 1 has the numerical data listed in Table 1 below:

Table 1

Lens 2 has the numerical data listed in Table 2 below:

Table 2

Lens 3 has the numerical data listed in Table 3 below:

Table 3

Lens 4 has the numerical data listed in Table 4 below:

Table 4

Lens 5 has the numerical data listed in Table 5 below:

Table 5

Lens 6 has the numerical data listed in Table 6 below:

Table 6

Lens 7 has the numerical data listed in Table 7 below:

Table 7

Lens 8 has the numerical data listed in Table 8 below:

Table 8

Lens 9 has the numerical data shown in Table 9 below:

Table 9

Denote therein

f is the focal length of the lens,

r [deep] 1 to r [deep] 13 are the radii of curvature of the lens surfaces,

d [deep] 1 to d [deep] 12 are the thicknesses of the lenses or the air gaps between them,

n [deep] 1 to n [deep] 8 are the refractive indices of the lenses,

small Ny [deep] 1 to small Ny [deep] 8 the Abbe numbers of the lenses,

N / A. the numerical aperture,

small beta the magnification and

W.D. the working distance.

Claims (9)

1. Microscope objective for 40x magnification, which consists of a first lens element in the form of a thick meniscus-shaped diverging lens with a concave surface on the object side, a second lens element in the form of a meniscus-shaped converging lens with a concave surface on the object side, a third lens element in the form of a converging cemented element, a fourth lens element in Form of a converging cemented element and a fifth lens element in the form of a dispersing meniscus-shaped cemented element with a concave surface on the image side, characterized by the following data: Table 1 or by values that, based on this data set, result from variation due to a variation of one of the following variables (1) - (9) in which denote f is the focal length of the lens, r [deep] 1 to r [deep] 13 are the radii of curvature of the lens surfaces, d [deep] 1 to d [deep] 12 are the thicknesses of the lenses or the air gaps between them, n [deep] 1 to n [deep] 8 are the refractive indices of the lenses, small Ny [deep] 1 to small Ny [deep] 8 the Abbe numbers of the lenses, N / A. the numerical aperture, small beta the magnification, W.D. the working distance. 2. Microscope objective for 40x magnification, which consists of a first lens element in the form of a thick meniscus-shaped diverging lens with Concave surface on the object side, consisting of a second lens element in the form of a meniscus-shaped convergent lens with a concave surface on the object side, a third lens element in the form of a convergent cemented element, a fourth lens element in the form of a convergent cemented element and a fifth lens element in the form of a divergent meniscus-shaped cemented element with a concave surface on the image side , characterized by the following data: Table 2 or by values that, based on this data set, result from variation due to a variation of one of the following variables (1) - (9) in which denote f is the focal length of the lens, r [deep] 1 to r [deep] 13 are the radii of curvature of the lens surfaces, d [deep] 1 to d [deep] 12 are the thicknesses of the lenses or the air gaps between them, n [deep] 1 to n [deep] 8 are the refractive indices of the lenses, small Ny [deep] 1 to small Ny [deep] 8 the Abbe numbers of the lenses, N / A. the numerical aperture, small beta the magnification, W.D. the working distance. 3. Microscope objective for 40x magnification, which consists of a first lens element in the form of a thick meniscus-shaped diverging lens with a concave surface on the object side, and a second lens element in the form of a meniscus-shaped one A converging lens with a concave surface on the object side, a third lens element in the form of a converging cemented element, a fourth lens element in the form of a converging cemented element and a fifth lens element in the form of a dispersing meniscus-shaped cemented element with a concave surface on the image side, characterized by the following data: Table 3 or by values that, based on this data set, result from variation due to a variation of one of the following variables (1) - (9) in which denote f is the focal length of the lens, r [deep] 1 to r [deep] 13 are the radii of curvature of the lens surfaces, d [deep] 1 to d [deep] 12 are the thicknesses of the lenses or the air gaps between them, n [deep] 1 to n [deep] 8 are the refractive indices of the lenses, small Ny [deep] 1 to small Ny [deep] 8 the Abbe numbers of the lenses, N / A. the numerical aperture, small beta the magnification, W.D. the working distance. 4. Microscope objective for 40 times magnification, which consists of a first lens element in the form of a thick meniscus-shaped diverging lens with a concave surface on the object side and a second lens element in the form of a meniscus-shaped one A converging lens with a concave surface on the object side, a third lens element in the form of a converging cemented element, a fourth lens element in the form of a converging cemented element and a fifth lens element in the form of a dispersing meniscus-shaped cemented element with a concave surface on the image side, characterized by the following data: Table 4 or by values that, based on this data set, result from variation due to a variation of one of the following variables (1) - (9) in which denote f is the focal length of the lens, r [deep] 1 to r [deep] 13 are the radii of curvature of the lens surfaces, d [deep] 1 to d [deep] 12 are the thicknesses of the lenses or the air gaps between them, n [deep] 1 to n [deep] 8 are the refractive indices of the lenses, small Ny [deep] 1 to small Ny [deep] 8 the Abbe numbers of the lenses, N / A. the numerical aperture, small beta the magnification, W.D. the working distance. 5. Microscope objective for 40x magnification, which consists of a first lens element in the form of a thick meniscus-shaped diverging lens with a concave surface on the object side and a second lens element in the form of a meniscus-shaped one A converging lens with a concave surface on the object side, a third lens element in the form of a converging cemented element, a fourth lens element in the form of a converging cemented element and a fifth lens element in the form of a dispersing meniscus-shaped cemented element with a concave surface on the image side, characterized by the following data: Table 5 or by values that, based on this data set, result from variation due to a variation of one of the following variables (1) - (9) in which denote f is the focal length of the lens, r [deep] 1 to r [deep] 13 are the radii of curvature of the lens surfaces, d [deep] 1 to d [deep] 12 are the thicknesses of the lenses or the air gaps between them, n [deep] 1 to n [deep] 8 are the refractive indices of the lenses, small Ny [deep] 1 to small Ny [deep] 8 the Abbe numbers of the lenses, N / A. the numerical aperture, small beta the magnification, W.D. the working distance. 6. Microscope objective for 40 times magnification, which consists of a first lens element in the form of a thick meniscus-shaped diverging lens with a concave surface on the object side, and a second lens element in the form of a meniscus-shaped one A converging lens with a concave surface on the object side, a third lens element in the form of a converging cemented element, a fourth lens element in the form of a converging cemented element and a fifth lens element in the form of a dispersing meniscus-shaped cemented element with a concave surface on the image side, characterized by the following data: Table 6 or by values that, based on this data set, result from variation due to a variation of one of the following variables (1) - (9) in which denote f is the focal length of the lens, r [deep] 1 to r [deep] 13 are the radii of curvature of the lens surfaces, d [deep] 1 to d [deep] 12 are the thicknesses of the lenses or the air gaps between them, n [deep] 1 to n [deep] 8 are the refractive indices of the lenses, small Ny [deep] 1 to small Ny [deep] 8 the Abbe numbers of the lenses, N / A. the numerical aperture, small beta the magnification, W.D. the working distance. 7. Microscope objective for 40 times magnification, which consists of a first lens element in the form of a thick meniscus-shaped diverging lens with a concave surface on the object side, and a second lens element in the form of a meniscus-shaped one A converging lens with a concave surface on the object side, a third lens element in the form of a converging cemented element, a fourth lens element in the form of a converging cemented element and a fifth lens element in the form of a dispersing meniscus-shaped cemented element with a concave surface on the image side, characterized by the following data: Table 7 or by values that, based on this data set, result from variation due to a variation of one of the following variables (1) - (9) in which denote f is the focal length of the lens, r [deep] 1 to r [deep] 13 are the radii of curvature of the lens surfaces, d [deep] 1 to d [deep] 12 are the thicknesses of the lenses or the air gaps between them, n [deep] 1 to n [deep] 8 are the refractive indices of the lenses, small Ny [deep] 1 to small Ny [deep] 8 the Abbe numbers of the lenses, N / A. the numerical aperture, small beta the magnification, W.D. the working distance. 8. Microscope objective for 40 times magnification, which consists of a first lens element in the form of a thick meniscus-shaped diverging lens with a concave surface on the object side, and a second lens element in the form of a meniscus-shaped one A converging lens with a concave surface on the object side, a third lens element in the form of a converging cemented element, a fourth lens element in the form of a converging cemented element and a fifth lens element in the form of a dispersing meniscus-shaped cemented element with a concave surface on the image side, characterized by the following data: Table 8 or by values that, based on this data set, result from variation due to a variation of one of the following variables (1) - (9) in which denote f is the focal length of the lens, r [deep] 1 to r [deep] 13 are the radii of curvature of the lens surfaces, d [deep] 1 to d [deep] 12 are the thicknesses of the lenses or the air gaps between them, n [deep] 1 to n [deep] 8 are the refractive indices of the lenses, small Ny [deep] 1 to small Ny [deep] 8 the Abbe numbers of the lenses, N / A. the numerical aperture, small beta the magnification, W.D. the working distance. 9. Microscope objective for 40x magnification, which consists of a first lens element in the form of a thick meniscus-shaped diverging lens with a concave surface on the object side, and a second lens element in the form of a meniscus-shaped one A converging lens with a concave surface on the object side, a third lens element in the form of a converging cemented element, a fourth lens element in the form of a converging cemented element and a fifth lens element in the form of a dispersing meniscus-shaped cemented element with a concave surface on the image side, characterized by the following data: Table 9 or by values that, based on this data set, result from variation due to a variation of one of the following variables (1) - (9) in which denote f is the focal length of the lens, r [deep] 1 to r [deep] 13 are the radii of curvature of the lens surfaces, d [deep] 1 to d [deep] 12 are the thicknesses of the lenses or the air gaps between them, n [deep] 1 to n [deep] 8 are the refractive indices of the lenses, small Ny [deep] 1 to small Ny [deep] 8 the Abbe numbers of the lenses, N / A. the numerical aperture, small beta the magnification, W.D. the working distance.